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The 2030 Agenda for Sustainable Development Goals of the United Nations puts forward a transformational vision to cope with food security, nutrition, and health challenges, in which sweet potato can play an important role. Globally, sweet potato production is valued at $53.83 billion. The Agricultural Research Council of South Africa (ARC) sweet potato research and development (R&D) program over the past seven decades delivered 31 genetically improved cultivars via demand‐led breeding, managed the collection and maintenance of 375 accessions, contributed toward the optimization of cultivation practices, developed crop protection and diagnostic services, and provided streamlined seed systems and technology transfer in processing and enterprise development. The ARC's work is part of a large number of interdependent global programs committed to improving livelihoods and nutrition through sweet potato. This review shares and analyses major achievements, highlights unique research contributions achieved through partnerships, and discusses bottlenecks on funding and uptake of technologies. New research imperatives will involve root phenotyping, employing marker‐based technologies, and genome‐wide association studies through new funding received recently. Exploration of the commercialization potential of processed products made from orange‐fleshed sweet potato will be a major focus of the R&D program. Expansion of partnerships, marketing, and financing will be important for future contribution of sweet potato to the economy. Core Ideas: Sweet potato has great potential to address several Sustainable Development Goals of the United Nations.A comprehensive sweet potato research and development program described herein provided technology across the full value chain.Screening methods for wilt disease, nematodes, protein content, virus, and crop development are highlighted.Expansion of partnerships and financing is essential to retain research momentum.Modern technologies must be key in new research imperatives.This article provides important lessons for public breeding efforts. [ABSTRACT FROM AUTHOR]

Cassava (Manihot esculenta Crantz) is an important root crop worldwide. It is adapted to a wide range of environmental conditions, exhibiting differential genotypic responses to varying environmental conditions. The objectives of this study were: (1) to examine the effect of genotype, environment and genotype × environment interaction (GEI) on fresh root yield (FRY) and dry matter content (DMC); and (2) to identify superior genotypes that exhibit high performance for the traits of interest using the genetic tools of additive main effects and multiplicative interaction (AMMI) and genotype stability index (GSI) analysis. Eleven cassava genotypes were evaluated in a randomized complete block design at six trial sites in South Africa. The combined analysis of variance based on AMMI revealed significant genotype, environment and GEI for the traits. The percentage variation due to GEI was higher than the percentage variation due to genotype for FRY, reflecting differential genotypic responses across the experimental sites. The proportion of variance due to genotype variation was larger for DMC. Genotype stability index (GSI) showed that UKF3 (G6), 98/0002 (G2) and P4/10 (G5) were the highest yielding and most stable genotypes for FRY, and 98/0002 (G1), UKF3 (G6) and UKF9 (G11) were the highest yielding and most stable genotypes for DMC. Cultivars 98/0002 and UKF3 were identified as providing high stability with superior fresh root yield and DMC. These genotypes could be recommended to farmers for food, feed and industrial applications without the need for further breeding. The AMMI-2 model clustered the testing environments into three mega-environments based on the winning genotypes for FRY and DMC. Mabuyeni (KwaZulu-Natal), Shatale (Mpumalanga) and Mandlakazi (Limpopo) would be the best testing sites in future cassava-genotype evaluation and breeding programs. This study provides a baseline for a future study on the GEI of cassava varieties, using a larger set of genotypes, factoring in seasonal variation. [ABSTRACT FROM AUTHOR]

Cassava is an important starchy root crop grown globally in tropical and subtropical regions. The ability of cassava to withstand difficult growing conditions and long-term storability underground makes it a resilient crop, contributing to food and nutrient security. This study was conducted to evaluate the performance and adaptability of exotic cassava cultivars across different environments in South Africa and to recommend genotypes for cultivation. A total of 11 cassava cultivars were evaluated at six on-farm sites, using a randomized complete block design with three replications. There were highly significant (p < 0.001) variations between genotypes, environments, and their interaction for all yield and yield-related traits studied. This indicates the need to test the genotypes in multiple environments before effective selection and commercialization can be undertaken. MSAF2 and UKF4 showed the overall best performances for most of the traits, whilst UKF9 (49.5%) and P1/19 (48.5%) had the highest dry matter yield. UKF4 (102.7 t ha−1) had the highest yield and greatest root yield stability across environments. MSAF2 did not perform consistently across environments because it was highly susceptible to cassava mosaic disease (CMD). MSAF2 could be used as a donor parent to generate novel clones with large numbers of marketable roots, and high fresh root yields, if the other parent can provide effective resistance to CMD. Based on genotype and environmental mean, Mabuyeni (KwaZulu-Natal), Mandlakazi (Limpopo), and Shatale (Mpumalanga) were found to be better environments for cassava cultivation and testing. This study is a pioneer in cassava research using multiple environments in South Africa. It provides baseline information on the performance of currently available cassava clones, their adaptation to multiple sites, the identification of suitable test sites, and information on current genetic resources for a future breeding program. [ABSTRACT FROM AUTHOR]

Sweet potato is an important world staple with the potential to address hunger and malnutrition. The Agricultural Research Council of South Africa has led sweet potato breeding efforts in the country since 1952 and released several important cultivars. More detailed quality assessments are necessary in addition to general breeding criteria. The present study investigated sweet potato cultivars and elite clones for (1) their nutritional composition; (2) biochemical reaction to drought stress; (3) correlate biochemical reaction to root yield for possible identification of screening methods for drought tolerance in sweet potato. Orange-fleshed cultivars, in particular Bophelo, had superior contents of Fe, Zn, Mg, Ca, Mn, and dietary fiber. Cream-fleshed cultivars, particularly Ndou, were higher in starch and carbohydrate. When sweet potato cultivars were subjected to drought stress, significant changes were noted in most antioxidant enzymes, chlorophyll and proline concentrations, and 13C discrimination. All of these showed significant correlations with root yield. For screening of drought tolerance, the determination of nitrate reductase, proline, and chlorophyll concentrations at 60 days after planting are recommended. Ndou was less affected by drought stress. Bophelo and Ndou, which are gaining popularity on the informal market, have superior nutritional value and are good cultivar choices for food security and addressing malnutrition. [ABSTRACT FROM AUTHOR]

Cassava (Manihot esculenta Crantz) is the sixth most important food crop and consumed by 800 million people worldwide. In Africa, cassava is the second most important food crop after maize and Africa is the worlds' largest producer. Though cassava is not one of the main commodity crops in South Africa, it is becoming a popular crop among farming communities in frost-free areas, due to its climate-resilient nature. This necessitated the establishment of a multi-disciplinary research program at the Agricultural Research Council of South Africa. The objective of this review is to highlight progress made in cassava breeding and genetic analysis. This review highlights the progress of cassava research worldwide and discusses research findings on yield, quality, and adaptability traits in cassava. It also discusses the limitations and the prospects of the cassava R&D program towards development of the cassava industry in South Africa. [ABSTRACT FROM AUTHOR]

DNA fingerprinting is a molecular technique applied to identify genetic differences between plant cultivars or lines and is used for genetic purity testing. The suitability of single nucleotide polymorphism (SNP) panels for the fingerprinting of tetraploid potato were investigated as a new high throughput, objective, and cost-effective method instead of simple sequence repeats (SSRs) and polyacrylamide gel electrophoresis (PAGE). One-hundred and ninety (190) potato cultivars, including various cultivars currently important in South Africa, were genotyped at 500 SNP positions utilising SeqSNP by LGC Biosearch Technologies. An optimal panel of 25 SNP markers was identified that could discriminate between South African potato cultivars on genetic allele dosage. The genotypes of these SNPs were validated on selected potato genotypes using KASP (Kompetitive Allele Specific PCR) SNP assays. A database of SNP genotype profiles was compiled for all the entries of the germplasm database. The panel of 21 successful SNPs accurately identified the unique potato cultivars in the database. The KASP SNP assays of the successful SNP panel are therefore available for potato DNA fingerprinting as new germplasm, or purity test requests are submitted to ARC-VIMP. This panel provides an objective method for assigning putative cultivar identity to unknown samples submitted for fingerprinting. [ABSTRACT FROM AUTHOR]

Summary: Traditional crops have historically provided accessible and affordable nutrition to millions of rural dwellers but have been neglected, with most modern agricultural systems over‐reliant on a small number of internationally traded crops. Traditional crops are typically well‐adapted to local agro‐ecological conditions and many are nutrient‐dense. They can play a vital role in local food systems through enhanced nutrition (particularly where diets are dominated by starch crops), food security and livelihoods for smallholder farmers, and a climate‐resilient and biodiverse agriculture. Using short‐read, long‐read and phased sequencing technologies, we generated a high‐quality chromosome‐level genome assembly for Amaranthuscruentus, an under‐researched crop with micronutrient‐ and protein‐rich leaves and gluten‐free seed, but lacking improved varieties, with respect to productivity and quality traits. The 370.9 Mb genome demonstrates a shared whole genome duplication with a related species, Amaranthushypochondriacus. Comparative genome analysis indicates chromosomal loss and fusion events following genome duplication that are common to both species, as well as fission of chromosome 2 in A. cruentus alone, giving rise to a haploid chromosome number of 17 (versus 16 in A. hypochondriacus). Genomic features potentially underlying the nutritional value of this crop include two A. cruentus‐specific genes with a likely role in phytic acid synthesis (an anti‐nutrient), expansion of ion transporter gene families, and identification of biosynthetic gene clusters conserved within the amaranth lineage. The A. cruentus genome assembly will underpin much‐needed research and global breeding efforts to develop improved varieties for economically viable cultivation and realization of the benefits to global nutrition security and agrobiodiversity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Globally, the importance of bananas for food security is well known and documented. [•] Use of the micropropagation technique helps to meet increasing demand for bananas. [•] High rate of somaclonal variants remain a major bottleneck during micropropagation. [•] The role of BA and topolins on genetic fidelity was compared at same concentration. [•] Some topolins could reduce genetic variability among micropropagated plantlets. [ABSTRACT FROM AUTHOR]

Abstract: The effect of five topolins (meta-Topolin= mT; meta-Topolin riboside= mTR; meta-Methoxy topolin=MemT; meta-Methoxy topolin riboside=MemTR and 6-(meta-methoxy)-9-(tetrahydropyran-2-yl)-topolin=MemTTHP) on the photosynthetic pigments and leaf structures of micropropagated ‘Williams’ bananas was compared with the commonly used benzyladenine (BA). Surface-decontaminated explants were cultured for 70 d on modified Murashige and Skoog (MS) basal medium and supplemented with 10, 20 or 30μM cytokinins (CKs). At 10 d intervals, the photosynthetic pigments were quantified via spectrophotometric methods for 7 cycles. Generally, the maximum pigment content was attained between 40 and 50 d. The control plantlets had the highest pigment content (1150μg/g FW). Among the CKs, 10μM MemTTHP generally had the best pigment stimulatory effect at the same period. After 40 d, scanning electron microscopy (SEM) of the foliar surface showed that the stomata density was highest in 10μM MemTTHP-treated and lowest in 10μM MemTR-treated plantlets. The stomatal structure and pore area also varied with the type and concentration of CK added. Generally, prolonging culture duration as well as increasing CK concentrations reduced the pigment content. However, the drastic breakdown in chlorophyll pigments beyond 50 d was slightly inhibited by the presence of mT, mTR, MemTTHP and BA compared to the control. The CK-treated plantlets at equimolar concentration had comparable chlorophyll a/b and total chlorophyll/carotenoid ratios after 10 d; probably as an adaptive measure. At the end of the current study, 10μM mT and mTR plantlets remained green as reflected by the higher total chlorophyll/carotenoid ratio as well as by the visual observations. A well-developed photosynthetic apparatus enhances the survival of in vitro plantlets during the acclimatization stage. Current findings provide some insight into the role of meta-topolins on photosynthetic parameters in vitro, which inevitably partly contributed to the better acclimatization capability of meta-topolin-regenerants. [Copyright &y& Elsevier]

A study was done to investigate the effects of some physical and chemical factors on growth and development of Aloe ferox ex vitro and in vitro. The effects of light, temperature, and smoke-water on seed germination, ex vitro seedling growth requirements, and effect of germination medium and cytokinins on shoot induction and multiplication in vitro were investigated. The highest germination percentage of A. ferox seeds was recorded between 15 and 30 °C. Seed germination was inhibited at 10 and 35 °C. There was a nonsignificant increase in germination percentage (78%) for seeds that were germinated under constant dark conditions. Smoke-water-treated seeds showed significant improvement in percentage germination (80%) over the control (66%) at 25 °C with a 16-h photoperiod. Seedlings of A. ferox subjected to alternating temperatures (30/15 °C) or being irrigated three times weekly at 25 °C showed better seedling growth. In an in vitro experiment, seedlings germinated in distilled water and one-tenth strength Murashige and Skoog medium had superior shoot induction competence compared with the other germination media. The cytokinins meta-Topolin (mT) and meta-Topolin riboside (mTR) at 5 µM gave significantly higher shoot multiplication rates compared with the control and benzyladenine (BA)-treated plants. A higher abnormality index was recorded for BA-treated plants. The findings of this study will be beneficial for commercial propagation of Aloe ferox. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the type and concentration of plant growth regulators and sub-culturing on somaclonal variation were studied in Cavendish banana cv. ‘Zelig’ obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the fourth multiplication cycle were used for the investigation. Auxins (IAA, IBA and NAA) and cytokinins (BA and TDZ) were used to multiply shoots for 10 generations. Bands generated through RAPD-PCR were scored according to whether they were present (1) or absent (0) to determine the extent of somaclonal variation. Results were then analyzed using cluster analysis. The relationship between multiplication rate and somaclonal variation was assessed using correlation analysis. Results indicated that treatments with higher multiplication rates produced more variants; sometimes as high as 72%. Dwarf off-types accounted for 88% of the variation. A dwarf-specific band, about 1500kb in size, was amplified by the primer OPC-15. The band appeared consistently in normal plants but was absent in all dwarf plants. [Copyright &y& Elsevier]

Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally accepted taxa within the genus, including some endemic species. Using Hypoxis hemerocallidea as a case study, this review addresses the conservation concerns arising from the unsustainable, wild harvesting of a number of Hypoxis species. Hypoxis hemerocallidea is one of the wild-harvested, economically important, indigenous medicinal plants of southern Africa, with potential in natural product and drug development. There are several products made from the species, including capsules, tinctures, tonics and creams that are available in the market. The use of H. hemerocallidea as a "cure-all" medicine puts an important harvesting pressure on the species. Unsustainable harvesting causes a continuing decline of its populations and it is therefore of high priority for conservation, including a strong case to cultivate the species. Reviewing the current knowledge and gaps on cultivation of H. hemerocallidea, we suggest the creation of a platform for linking all the stakeholders in the industry. [ABSTRACT FROM AUTHOR]

Highlights: [•] A total of 47 endogenous cytokinin-forms grouped into 9 classes were quantified. [•] Tissue-cultured plants had more endogenous cytokinin levels than acclimatized plants. [•] 9-Glucosides were the major metabolites in tissue-cultured and acclimatized plants. [Copyright &y& Elsevier]

Abstract: Merwilla plumbea (Lindl.) Speta is an important medicinal plant widely used in traditional medicine. We evaluated the effect of five cytokinins [benzyladenine (BA), 2-isopentenyladenine (2iP), meta-topolin (mT), meta-topolin riboside (mTR), and meta-methoxy-9-tetrahydropyran-2-yl-topolin (MemTTHP)] on the level of phenolic acids and antioxidant activity of M. plumbea during the tissue culture and acclimatization stages. Two cytokinins (mT and mTR) significantly improved the antioxidant activity of tissue culture plantlets while the control plantlets were better after acclimatization. Using UPLC–MS/MS, the levels of hydroxybenzoic and hydroxycinnamic acid derivatives (phenolic acids) varied significantly during tissue culture and acclimatization, depending on the cytokinin and plant part analyzed. Vanillic acid (24.9μgg−1) detected in underground parts of tissue culture plants supplemented with BA was the most abundant phenolic acid detected. The current findings indicate that the phytochemicals together with the bioactivity during in vitro propagation of M. plumbea is influenced by the cytokinin type used and the stage of plant material collection. [Copyright &y& Elsevier]